More than 30 years after President Richard Nixon declared a "War on Cancer," the battle is as heated as ever. Doctors, researchers, and patients are staging an all-out assault on the disease, and they're scoring some amazing victories.

Thanks to a combination of better treatments, early detection, and a commitment to prevention, more and more people are surviving cancer. According to the National Cancer Institute, death rates for lung cancer, colorectal cancer, breast cancer and prostate cancer - the four leading causes of cancer-related deaths - are all on the decline. More than half of cancer deaths, however, are still from these four. Deaths from all types of cancer took a downturn in the mid-1990s and show no sign of rising again.

Any victory celebration is premature, however: Despite much progress, cancer still kills more than 500,000 Americans every year. Researchers continue to look for ways to save more lives, and they won't stop until every cancer patient becomes a cancer survivor. With dozens of promising new treatments on the market and hundreds more in the research pipeline, the ultimate goal has never been closer.

Of course, cancer prevention is as important as ever. Diet and a sedentary lifestyle are related to about one-third percent of all cancer deaths -- and 30 percent of cancer deaths can be attributed to smoking, according to the American Cancer Society. Early screening is also important. Although some forms remain controversial, it's also true, for example, that most colon cancer deaths could be prevented with available screening tests. So among the most important fronts in the War on Cancer are probably primary prevention through behavior change, with help from simple screening tests.

Here's a look at some of the latest developments in the war on cancer:

It's well-known that exercise plays an important role in preventing heart disease. But more recently research showed that physical activity may reduce your risk of cancer as well. The best ways for nonsmoking individuals to reduce their cancer risk is to exercise regularly and eat a diet rich in fruits and vegetables and low in saturated fat, according to the American Cancer Society. The ACS recommends 30 minutes of moderate physical activity five or more times a week, and even more exercise may help reduce the risks of breast and colon cancer. (Children should exercise at least an hour for five or more days a week.) You should also eat at least five servings of fruits and vegetables a day, according to the American Cancer Society.

Smoking is still the major single cause of cancer deaths in the United States, so for smokers, quitting is the best way to reduce your cancer risk.

Finally, protecting yourself against sunburn and ultraviolet rays reduces the risk of most skin cancers, including melanomas. Recently, however, experts have suggested getting 15 or 20 minutes of early morning or late afternoon sun, since sunlight helps your body produce vitamin D.

Early detection of cancer can often make the difference between a treatable disease and a fatal illness. Not surprisingly, researchers are pushing to improve their ability to diagnose cancer as early as possible. They are also using the results of recent studies to fine tune guidelines for cancer screening. Here's the latest news on screening tests for common cancers:

•Breast cancer. Researchers are studying new techniques for early detection of breast cancer, but mammograms are still the number one screening tool. In fact, support for mammograms is stronger than ever. In 2002, the U.S. Department of Health and Human Services urged all women 40 and over to have a screening mammogram every one to two years. Previous DHHS guidelines called for mammograms starting at age 50. The American Cancer Society recommends yearly mammograms starting at age 40. Many experts believe that regular mammograms and early detection are largely responsible for the recent decline in breast cancer deaths.

Most groups recommend mammography starting at age 40 now. However, there are many false positives and false negatives, especially in younger women, who have lower overall incidence of the disease and who have denser breasts that make mammography less sensitive. (Just remember, mammography for 10 years in women aged 40 to 50 is thought to save the lives of about one in 1,800 women. For women aged over 50, it's about one in 800.) For women at high risk for breast cancer, the American Cancer Society recommends both a mammogram and an MRI every year.

•Prostate cancer. For men over 50, PSA (prostate-specific antigen) tests have become commonly ordered by physicians, but there is medical controversy over their use. This simple blood test can alert doctors to a hidden case of prostate cancer, but although the test has been around since the 1980s, surprisingly, it has never been shown to save lives. Cancers in the prostate are often slow growing and pose little threat. When the cancer is more aggressive, even early detection may not be enough to save a man's life.

The American Cancer Society recommends that all men over 50 who are expected to live for at least ten more years be offered the PSA and the digital rectal exam (DRE) every year. They should be informed about benefits and limitations of PSA testing so they can make an informed decision with their doctor about whether or not to undergo the test.

Discussing the controversy over prostate cancer screening, Michael Potter, MD, a family practitioner with the University of California at San Francisco Medical Center, explains that a 50-year-old man currently has a 42 percent risk of having a diagnosis of prostate cancer by the time he dies -- if he lives to 80, he has at least a 70 percent chance of dying of cancer. However, that same 50-year-old man has a 3 percent chance of dying from prostate cancer.

"We take this to mean that many prostate cancers don't need to be diagnosed or treated," Potter says. "The tests we have right now don't tell us very well which men are the ones who could benefit from treatment, and the treatments often have side effects, such as impotence and incontinence. And it will still be some time before we know for sure if the treatments available are of any help for men who receive an early diagnosis of prostate cancer. This is why prostate cancer screening is increasingly controversial."

•Colorectal cancer. Cancer of the rectum or colon is almost always treatable when detected early. For this reason, many experts believe that screening is an invaluable tool for preventing cancer death. Researchers are currently following 155,000 patients nationwide to see exactly how many lives can be saved with regular screening. The final results won't be ready for more than a decade, but scientists have already established firm guidelines for screening.

According to the American Cancer Society and other organizations, men and women at average risk for colorectal cancer should undergo regular screening for the disease starting at age 50. (People at higher risk may need to start at an earlier age.) Screening tests include a fecal immunochemical test or a fecal occult blood test (a home test that checks for small amounts of blood hidden in stool) every year; a flexible sigmoidoscopy, a double contrast barium enema or a CT colonography (virtual colonoscopy) every five years; or a colonoscopy every 10 years. A stool DNA test is another screening option, although the ACS does not have a recommendation on the frequency of such tests.

There is already good evidence that early detection and removal of polyps and localized colorectal cancer can prevent a more advanced form of cancer in the vast majority of cases, and that existing screening methods can find many of these important lesions. Between 2000 and 2005, fewer than half of Americans over age 50 have had any screening -- which is probably the biggest single barrier to making a large reduction in the rates of colorectal cancer death in the U.S.

•Cervical cancer. The value of the Pap test as a lifesaving, early warning system for cervical cancer is beyond dispute. Before Pap tests were introduced, there were 20,000 cervical cancer deaths in the US per year -- now there are only about 3,800 cervical cancer deaths per year -- despite the fact that major risk factors have all increased. There are now higher rates of HPV, higher rates of sex, and higher rates of smoking, which doubles the risk of cervical cancer in HPV infected women. In countries where Pap tests are not done, cervical cancer deaths are at least as common as deaths from breast cancer. In the U.S., 50 to 70 percent of cervical cancer deaths are in women who have not had a Pap test in the last five years.) The simple test detects abnormal cells before they have a chance to turn cancerous.

The U.S. Preventive Services Task Force recommends Pap smears at least every three years for all women, starting within three years of their first intercourse or their 21st birthday, whichever comes first. Testing more often may be useful in some women who are at high risk. Testing generally isn't necessary for women who had their cervix removed in a hysterectomy (for benign disease) or for women over 65 who already had at least three normal pap smears in the last 10 years and have no other risk factors for cervical cancer.

In June 2006, the Food and Drug Administration (FDA) approved a new vaccine that protects against four types of HPV, including those linked to 70 percent of cervical cancer cases. The American Cancer Society now recommends routine vaccination for all girls aged 11 to 12.

Weapons against advanced breast cancer

Fall 2003 brought good news in the treatment of advanced breast cancer, which is generally attacked with hormonal therapy, cancer-killing chemotherapy, or a combination of both. As reported in the New England Journal of Medicine, Canadian researchers discovered that the hormonal agent Femara (letrozole) significantly cut the risk of breast cancer recurrence in post-menopausal women who had already completed five years of Nolvadex (tamoxifen) treatment. (Tamoxifen, a common hormonal treatment for women recovering from breast cancer, generally loses its effectiveness after five years.) Letrozole is one of a class of drugs called aromatase inhibitors, which includes the agents Arimidex (anastrozole) and Aromasin (exemestane).

Unlike chemotherapy, which targets cancer cells for destruction, hormonal therapy for cancer patients is designed to block the cancer cells' hormonal interactions in order to stop or slow down the proliferation of cancer cells (and potentially shrink tumors). Aromatase inhibitors act to lessen the amount of estrogen secreted by women's fat and muscle cells that would normally give a signal for cancer cells to grow when they reach their target receptors.

According to the publication CURE (Cancer Updates, Research, and Education), aromatase inhibitors are increasingly common as front-line choices for treating postmenopausal women with advanced breast cancer. Side effects, which can include hot flashes and joint aches, tend to be mild. For women who have relapsed despite multiple hormonal treatments, the hormone drug Faslodex (fulvestrant) may provide an alternative to "chemo": in one study of advanced breast cancer patients treated with either tamoxifen or an aromatase inhibitor, Faslodex was linked to shrunken tumors in 41 percent of cases.

CURE also had good news for regular cancer patients. "While chemotherapy previously meant side effects such as hair loss and nausea, the newer chemotherapies are kinder, gentler, and even more effective at curing or controlling disease than in the past," the journal noted. Among them are the taxanes Taxol (paclitaxel) and Taxotere (docetaxal), with new formulations and dosing schedules that appear to have lessened side effects such as allergic reactions.

Harnessing the power of the immune system

The human immune system has always been one of the most effective weapons against cancer. Now, scientists are working to make our natural cancer-killers even more powerful. A class of drugs called biologics fights cancer by boosting the strength of the immune system. Interleukin 2 (aldesleukin), one of these biologics, has already been approved for the treatment of metastatic (invasive) cases of kidney cancer and melanoma. Because of its severe side effects, however, it is not widely used. Researchers are investigating the use of biologics for the treatment of a wide range of cancers, including colorectal, breast, prostate, lung, and brain.

Vaccines are another promising approach to preventing or fighting cancer. There are currently two vaccines in use that fight viruses that can lead to cancer: the hepatitis B vaccine, which by preventing hepatitis B may also prevent some liver cancers that are due to chronic infection with the virus; and GardasilTM, which prevents infection with certain types of the human papillomavirus (HPV) that cause about 70 percent of cervical cancer cases. Hepatitis C is reaching epidemic proportions in the U.S. If a vaccine for hepatitis C is found, it may also affect rates of liver cancer, a disease that's been linked to hepatitis C infection.

And as amazing as it sounds, doctors may someday even be able to fight cancer with vaccines. Like shots given to ward off measles or whooping cough, cancer vaccines would be designed to help the immune system recognize and destroy rogue cells. Unlike standard vaccines, the cancer shots would be given AFTER the disease is diagnosed. Researchers are currently testing vaccines for many types of cancer. Among those being researched is a vaccine for stomach cancer, which is often associated with a bacteria called Helicobacter pylori.

Drugs that starve tumors

If you picked up a newspaper in the late 1990s, you probably read about a supposed "magic bullet" for cancer. Headlines touted a new class of drugs that could starve tumors by blocking off their blood supply. Early trials of these drugs -- known as angiogenesis inhibitors -- were unusually successful, at least in laboratory mice. Unfortunately, human cancers proved to be much harder targets. Early trials in humans were disappointing, but the FDA has approved several angiogenesis inhibitors. One – Avastin – has been used in the treatment of colon cancer that has spread, some non-small cell lung cancers, and breast cancers that have spread. Other angiogenesis inhibitors are now undergoing clinical trials to treat a wide range of cancers.

Lasers: The cutting edge of cancer surgery

While scalpels still have their place in operating rooms, lasers -- highly intense and precisely focused beams of light -- have recently become important tools for cancer surgery. Lasers can make extremely precise incisions and can shrink or destroy many types of tumors. Lasers are most commonly used to treat cancers in easy-to-reach places such as the skin, vocal cords, or cervix. They also can be used to shrink or destroy a tumor, for example one that is blocking a person’s windpipe or esophagus, or to remove colon polyps. In some cases, endoscopes can be used to direct lasers to more out-of-the-way organs such as the lungs.

At this time, relatively few surgeons have expertise in laser surgery, but their ranks are growing. Already laser therapy is used to treat esophageal cancer. Researchers are currently studying laser surgery for the treatment of other forms of cancer, including cancer of the brain and prostate.

With so many new treatments and so many more on the way, these are hopeful times for cancer patients, their families, and their doctors. New treatments also mean new choices. If you've been diagnosed with cancer, you'll have to carefully consider all of your treatment options. By working with your doctor, you can do your own part in the war against cancer.

-- Chris Woolston, MS, is a health and medical writer with a master's degree in biology. He is a contributing editor at Consumer Health Interactive, and was a staff writer at Hippocrates, a magazine for physicians. His reporting for CHI on occupational health earned him an award from the Northern California Society of Professional Journalists.

References

First published March 22, 2004
Last updated May 6, 2008
Copyright © 2004 Consumer Health Interactive

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